Norweb decided to accept the price curb rather than be referred to the Monopolies and Mergers Commission but must now reduce costs more than previously planned.
Of the 12 regional electricity companies in England and Wales, only South Wales has yet to accept the controls. Norweb, which announced last year it would cut 1,200 jobs by the end of the decade, said that the latest redundancies will effect marketing, industrial and support services staff.
Ken Harvey, chairman, said: "I hoped last summer's change in the price control would give our electricity businesses much needed stability until the year 2000, but the regulator has further reduced our allowed income.
"This is despite having the lowest domestic electricity tariffs in the UK.
"The loss of another 450 jobs for the North-west is something I very much regret, but I hope we are able to achieve the reductions by voluntary means."